Human behaviour and residual malaria transmission in Zanzibar: findings from in-depth interviews and direct observation of community events

Abstract

Background: Zanzibar has maintained malaria prevalence below 1% for the past decade, yet elimination remains elusive despite high coverage of core vector control interventions. As part of a study investigating the magnitude and drivers of residual transmission in Zanzibar, qualitative methods were utilized to better understand night time activities and sleeping patterns, individual and community-level risk perceptions, and malaria prevention practices.

Methods: A total of 62 in-depth interviews were conducted with community members and local leaders across six sites on Unguja Island, Zanzibar. Twenty semi-structured community observations of night-time activities and special events were conducted to complement interview findings. Data were transcribed verbatim, coded, and analysed using a thematic approach.

Results: Participants reported high levels of ITN use, but noted gaps in protection, particularly when outdoors or away from home. Routine household and community activities were common in evenings before bed and early mornings, while livelihood activities and special events lasted all or most of the night. Gender variation was reported, with men routinely spending more time away from home than women and children. Outdoor sleeping was reported during special events, such as weddings, funerals, and religious ceremonies. Participants described having difficulty preventing mosquito bites while outdoors, travelling, or away from home, and perceived higher risk of malaria infection during these times. Travel and migration emerged as a crucial issue and participants viewed seasonal workers coming from mainland Tanzania as more likely to have a malaria infection and less likely to be connected to prevention and treatment services in Zanzibar. Some community leaders reported taking the initiative to register seasonal workers coming into their community and linking them to testing and treatment services.

Conclusions: Targeting malaria interventions effectively is critical and should be informed by a clear understanding of relevant human behaviour. These findings highlight malaria prevention gaps in Zanzibar, and the importance of identifying new approaches to complement current interventions and accelerate the final phases of malaria elimination. Development and deployment of complementary interventions should consider human behaviour, including gender norms, that can influence exposure to malaria vectors and prevention practices. Expansion of community-level programmes targeting travellers and seasonal workers should also be explored.

Keywords: Elimination; Human behavior; Imported case; Malaria; Migration; Outdoor biting; Qualitative research; Residual transmission; Sub-Saharan Africa; Travel.

Fig. 1

Map of study sites

Fig. 2

Photos of study sites. Clockwise starting from top left, the photos show Bwejuu, Charawe, Tunduni, Miwani, Mbaleni, and Donge Mchangani. Photos were taken during field work in December 2016 during the dry season

Fig. 3

Illustration of common night time activities that occur during times when local malaria vectors are active. This includes routine activities in the evening and early morning as well as livelihood activities and special events that can last throughout the night

Fig. 4

Photos of common night time activities. a A woman and her children sit outdoors on the verandah of their home; b community members gather outdoors to watch television; c a woman prepares mandazi (fried dough) indoors before bed to sell the next day; d a man and woman collect and package charcoal in the early evening; e women chant while others sleep on the floor during Dhikri, an all-night religious event

Fig. 5

A child sleeps in an open-air space during early evening hours